Single powder photographic developers



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SINGLE POWDER PHOTOGRAPHIC DEVELQPERS No Drawing. Application December 26, 1956 Serial No. 630,436

11 Claims. (Cl. 96-66) The present invention relates to single powder photographic developers in which all of the essential ingredients of the developer are intimately admixed in dry powder form and more particularly, to an improved alkaline stabilizer for such developers.

Photographic developers contain as their essential ingredients one or more organic developing agents such as hydroquinone, l-phenyl-B-pyrazolidone (phenidone), para-aminophenol hydrochloride, p-methylaminophenol sulfate (metol), pyrogallol, p-phenylene diamine and its N,N-dialkyl substituted derivatives, an alkali such as sodium carbonate, borax, sodium metaborate or the like, a preservative such as an alkali metal sulfite and an anti-foggant such as potassium bromide or sodium bromide. Under ordinary conditions of mixing and storage, such dry developers undergo a decomposition reaction which manifests itself by a color change to a deep brown and adversely affects the photographic activity of the developers. It has always been presumed that this decomposition was caused by the aerial decomposition of the developing agent in the presence of alkali.

The art has been aware ofthis phenomenon and etforts have been made to abate such decomposition by adding to single powder developer mixtures an acidic stabilizer such as phthalic acid, boric anhydride, metaboric acid, potassium metabisulfite and the like. While these various acid stabilizers serve to promote the keeping qualities of such developers, they do not lead to optimurn results, and developers containing these acidic stabilizers generally discolor within a period of two to three months. Moreover, all of these acidic substances have inherent disadvantages; they are sparingly soluble in water or dissolve very slowly; they react with such components as sulfites and carbonates to form gas which may build up objectionable pressures in sealed cans; their use requires additional alkali in the formula to maintain developer activity; their stabilizing action is seriously impaired when the individual chemicals contain absorbed moisture and/or when the admixture is subjected to humid conditions, and, they provide no noticeable stabilizing action in developers containing alkali metaborates.

It is known that lithium hydroxide has been used in photographic developers as an alkali, particularly for the preparation of highly concentrated liquid developers. When used for this purpose, the lithium hydroxide is employed in combination with other alkali hydroxides to insure that crystallization of developer ingredients does not take place at low temperatures.

We have now discovered that anhydrous lithium hydroxide is an effective stabilizer for single powder photographic developers either alone or in combination with said acid stabilizers. Single powder developers containing anhydrous lithium hydroxide alone or in combination with the usual acidic stabilizers constitute the purposes and objects of the present invention.

The developers which are contemplated herein conice sulting dry powder is to be used to make ajliter of de veloping solution:

Parts Lithium hydroxide (anhydrous) 0.2 to; 8 Organic developing agent -a 3 to 15 Alkali 1 5 to Preservative v p -30 to Anti-fogging agent a 0.3 to 2 Acid stabilizer (optional) 0.5 to 12 The photographic developing agent may be any ,of

those previously'lmentioned or any ofuthe commonly used developing agents such.,as-pyrocatechol, chlorohydroquinone (adurol), p -hydroxyphenylamino acetic acid (glycin), 2,4-diaminophenol*(amidoly These developing agents may be used alone or in admixture with each other. Typically, we may use a mixture-of metol and hydroquinone, metoland 1-phenyl-3 -pyrazolidone (phenidone), phenidone and hydroquinone -or phenidone, metoland hydroquinone.

The preservative is an alkali metal sulfite preferably sodium sulfite usually in its anhydrous condition, the antifoggins a n s s iumxorp tassium omid oz of the organic ntio in :a entsrsu has. 6.- n enzimidazole, S-nitrobenzimidazole, Z-mercaptqbe imidazole, S-chlorobenzimidazole, 6 ehlorobenzimidazole, tetrazole or benzotriazole. The alkali may be any of h e used n. comrcuudinsrhctcsranhi deve op such a od um garb .p tassiu wa b a e v on ium. tetraher sodium metahor te. d odium p a e. rthe arger f Sodium sulfit yap @lQQLLhk-Hfifi rforiqaddi tional alkalir n. which es;.theed msulfiteractsboth as n lkal anilap eserva ite. '1'

Among the si i tab ize whishleenhe ard not y those e mera ed eyeibutalso maleic anhydride, phthalic anhydride, benzoic anhydride, salicylic acid, phthalimide, saccharin, rand';anhydrous oxalic acid. In compounding the aforesaid developer mixtures, one may proceedbyfirst. mixing the ..acidic stabilizer or stabilizers, addingandadmixing the alkali, then'the developingagent. and finallythe other ingredients, adding the anhydrous lithium hydroxide .last. .However if'itbe preferred, all the ingredients maybe admixed simultaneously. The use, of. anhydrous lithium hydroxide offers many advantages andrepresents a marked improvement over the previously usedstabilizers. The fact thatlithium-hydroxide is a strong ,alkalimakes itpos sible to substitute all or part of the alkali normally used in a developer with a weaker alkali. For example, it is possible to use borax instead of sodium metaborate,bicarbonate instead of carbonate, and to use sodium sulfite without sodium carbonate. Moreover, single powder developers containing the usual acidic stabilizers absent the anhydrous,

lithium hydroxide discolorin a -period of a few months. When, however, the acidic stabilizers and-the anhydrous lithium hydroxide are present together in asingle powder developer, thestabilityof the developer is greatly magnifiedand no discolorationappears.even, after storing the developer for more than 12 months.

One of the most important advantages of anhydrous lithium hydroxide lies in the fact that its stabilizing action Patented-July 7, .1959- is not impaired to the extent of other known stabilizers when the chemicals are subjected to humid conditions such as during storage and blending. In this connection, it is noteworthy that anhydrous lithium hydroxide may be combinedwith sodium bisulfite 'or potassium metabisulfite to provide a truly superior stabilizing action. This is surprising in view of the fact that sodium bisulfite or potassium metabisulfite exert only a mild stabilizing action which is practically non-existent under humid conditions. Yet, it reinforces very markedly the much better stabilizing action of lithium hydroxide. Somewhat similar results are obtained by combining lithium hydroxide with such acidic stabilizers as phthalic acid and saccharin.

It is manifest, the facts being as stated, that the results must be attributable to some peculiar coaction between the anhydrous lithium hydroxide and the acidic stabilizer which serves to greatly intensify the stabilizing action of the acidic component, particularly of the alkali bisulfites and metabisulfites.

. The following examples will serve to illustrate our invention but are not restricted thereto. The quantity of the single powder developers represented by the following formulae is to be dissolved in suflicient water to give one liter of developer solution and the components are blended as previously indicated.

, Example I Gm. p-Methylaminophenol sulfate 0.75 Sodium sulfite (anhydrous) 11 Hydroquinone 3 Sodium carbonate (monohydrate) 16 Potassium bromide 0.5 Lithium hydroxide (anhydrous) 1.2

This paper developer which is free from acidic stabilizers kept for 6 months without discoloration or decomposition.

This borax containing fine-grain developer remained stable without discoloration for more than a year.

Example III Gm. Metol 1.5 Sodium sulfite (anhydrous) 80 Hydroquinone 3 Borax 3 Potassium bromide 0.5 Lithium hydroxide (anhydrous) 0.3 Potassium metabisulfite 1.6

This developer which contained lesser amounts of lithium hydroxide and potassium metabisulfite than the developer of Example H, did not show any discoloration after 6 months storage.

Example IV Gm. Metol 1.5 Sodium sulfite (anhydrous) 80 Hydroquinone 3 Boric acid I 1.9 Potassium bromide 0.5 Lithium hydroxide 0.35

This fine-grain developer which contained only lithium hydroxide as a stabilizer remained stable for more than 6 months.

'4 l Example V p-Methylaminophenol sulfate 4 Hydroquinone 10 Sodium sulfite (anhydrous) 45 Sodium carbonate (monohydrate) 64 Potassium bromide 0.9 Lithium hydroxide (anhydrous) 0.9 Phthalic acid 0.6 Potassium metabisulfite 1.5

This paper developer did not decolorize or show any other signs of decomposition when stored for more than a year.

Example Vl Gm. Metol 1.3 Hydroquinone 3.7 Sodium sulfite (anhydrous) 12.8 Sodium carbonate (monohydrate) 24 Potassium bromide 0.5 Lithium hydroxide (anhydrous) 0.8 Potassium metabisulfite 4 This energetic single-powder negative developer kept without decomposition or discoloration for more than a year.

Example VII This X-ray type single powder developer could be stored without decomposition for more than a year.

Example VIII Gm. Ethylenediamine tetracetic acid 0.8 Potassium metabisulfite 2 Phthalic acid 0.5 Phenidone 0.5 Hydroquinonc 9 Sodium sulfite (anhydrous) a- 67.5 Sodium carbonate (monohydrate) 45 Potassium bromide 2 Lithium hydroxide (anhydrous) 1.5 Potassium iodide 20 This single powder developer which serves as a first developer for color film of the reversal type could be stored for more than a year without decomposition or discoloration. If desired, an alkali thiocyanate on the order of (2-3 grams) sodium thiocyanate per liter may be added as a silver halide solvent.

Modifications of the invention will occur to persons skilled in the art. We, therefore, do not intend to be limited in the patent granted except as necessitated by the appended claims.

We claim:

1. A stable single powder photographic developer con taining, an organic silver halide developing agent, an alkali, a preservative, an anti-fogging agent and a stabilizing amount of anhydrous lithium hydroxide.

2. The composition as defined in claim 1, wherein said stabilizing amount is on the order of from 0.2 to 8 grams based on the amount of developer powder required to make up one liter of developer solution.

3. A stable single pwoder photographic developer cona n g a mixture of an organic silver halide developing agent, anhydrous lithium hydroxide, an alkali metal salt of sulfurous acid and an anti-fogging agent.

4. A stable single powder photographic developer containing in addition to an organic silver halide developing agent, an alkali, an alkali metal salt of sulfurous acid, an acidic stabilizing agent selected from the group consisting of boric anhydride, metaboric acid, phthalic anhydride, phthalic acid, salicylic acid, phthalimide, saccharin, maleic anhydride and anhydrous oxalic acid and an anti-foggant; a stabilizing amount of anhydrous lithium hydroxide.

5. A stable single powder photographic developer containing as its essential components for the preparation of a liter of developing solution:

Grams Lithium hydroxide (anhydrous) 0.2 to 8 Organic silver halide developing agent 3 to Alkali 5 to 100 Alkali metal sulfite 30.0 to 120 Anti-fogging agent 0.3 to 12 And an acid stabilizer selected from the group consisting of alkali bisulfites, alkali metal bisulfites, boric anhydride, mctaboric acid, phthalic anhydride, phthalic acid, salicylic acid, phthalimide, saccharin, maleic anhydride and anhydrous oxalic acid 0.5 to 12 Grams p-Methylaminophenol sulfate 1.5 Sodium sulfite (anhydrous) 80 Hydroquinone 3 Borax 3 Potassium bromide 0.5 Lithium hydroxide (anhydrous) 1.2 Potassium metabisulfite 6.4

8. A stable single powder developer having the following composition:

Grams p-Methylaminophenol sulfate 1.5 Sodium sulfite (anhydrous) Hydroquinone 3 Borax 3 Potassium bromide 0.5 Lithium hydroxide (anhydrous) 0.3 Potassium metabisulfite 1.6

9. A stable single powder developer having the following composition:

Grams p-Methylaminophenol sulfate 1.5 Sodium sulfite (anhydrous) 80 Hydroquinone 3 Boric acid 1.9 Potassium bromide 0.5 Lithium hydroxide (anhydrous) 0.35

10. A stable single powder developer having the fol- 11. A stable single powder developer having the following composition:

Grams p-Methylaminophenol sulfate 1.3 Hydroquinone 3.7 Sodium sulfite (anhydrous) 12.8 Sodium carbonate (monohydrate) 24 Potassium bromide 0.5 Lithium hydroxide (anhydrous) 0.8 Potassium metabisulfite 4 References Cited in the file of this patent UNITED STATES PATENTS Rasch et al. Mar. 27, 1956 OTHER REFERENCES Handbook of Chemistry and Physics, 38th ed. (1956- 57), page 540. 

1. A STABLE SINGLE POWDER PHOTOGRAPHIC DEVELOPER CONTAINING, AN ORGANIC SILVER HALIDE DEVALOPING AGENT, AN ALKALI, A PRESERVATIVE, AN ANTI-FOGGING AGENT AND A STABILIZAMOUNT OF ANHYDROUS LITHIUM HYDROXIDE. 